Orthopaedic implants and methods for making the same

ABSTRACT

Orthopaedic implants, orthopaedic implant sets, and/or methods for making the same. Aspects and embodiments of the present invention may include orthopaedic implants having an elongated insertion region including proximal, distal, and transition portions, wherein at least portions of at least one face each of the proximal and transition portions are defined by spaced apart constant radii of curvature. The same or other aspects and embodiments may include sets of orthopaedic implants in which proximal portions of the implants grow at different rates than distal portions of the implants. The same or other aspects and embodiments may include methods for making implants and/or sets of implants by studying the geometries of differently sized bony anatomies.

RELATED APPLICATIONS

This document claims the benefit of U.S. Provisional Application Ser.No. 60/679,283, entitled “Hip Femoral Implant” and filed May 9, 2005,the entire contents of which are incorporated by this reference.

RELATED FIELDS

Aspects and embodiments of the present invention relate to one or moreorthopaedic implants as well as methods for making one or moreorthopaedic implants.

BACKGROUND

Orthopaedic implants, such as femoral implants, tibial implants, humeralimplants, or others, can be installed in or otherwise associated withthe bony anatomy for treating traumatic injuries, reconstructing jointfunction, or for other purposes. Such implants may include an elongatedinsertion region, such as the stem region of a femoral hip implant,which can be at least partially inserted into the medullary canal of theproximal femur.

In some instances, the success of the orthopaedic implant may depend onhow well the elongated insertion region fits into the bony anatomy. Forexample, with a femoral hip stem, it is important that proximal portionsof the elongated insertion region fit tightly into the medullary canal,such that the stem loads proximal portions of the femur, preventing boneloss through stress shielding and/or resorption (and potentiallysubsequent failure of the implant). It is also important that distalportions fit snugly into the medullary canal; however, the fit shouldnot be so tight as to prevent proximal loading.

A good fit between the orthopaedic implant and its associated bonyanatomy may also help to prevent or lessen micromotion between theimplant and the bone. Excessive micromotion may also lead to implantfailure.

Because bone geometries vary from person to person (and may also varywith age), typical orthopaedic implants are often offered as part of aset or series of different sized implants. Typically, implant sets arecreated by first designing one size of implant and then scaling thatimplant in a proportional manner to define the geometries of the otherimplant sizes (e.g., increasing the width of the elongated insertionregion by a uniform amount along the entire length of the stem).

Typical implant system growth does not accurately reflect the geometriesof different bone sizes. Larger femurs, for example, are not simplybigger versions of smaller femurs. For instance, it has been discoveredthat proximal portions of the medullary canal (some or all of which maybe referred to as the metaphysis) may “grow” at a greater rate thandistal portions (some or all of which may be referred to as thediaphysis) as femoral size increases. Thus, femoral hip stem sets thatgrow the proximal portion at the same rate as the distal portion fromsize to size do not necessarily reflect the actual geometries of thevarious sizes of femurs. Thus, implant sets made in accordance withtraditional methodologies may, in some cases, fit poorly when installed,and may lead to implant failure for the reasons discussed above or forother reasons.

SUMMARY

Various aspects and embodiments of the present invention may provide fororthopaedic implants that more accurately reflect the actual geometriesof the various sizes of bony anatomies (such as the various sizes offemurs, tibias, humeri, or other bones).

In accordance with some embodiments, an implant may include an elongatedinsertion region for implanting into a medullary canal of the bonyanatomy. The elongated insertion region may include a proximal portionand a distal portion. The proximal portion may be designed and mayinclude geometries to have a desired fit in corresponding proximalportions of the medullary canal (such as, in some embodiments, themetaphysis). Similarly, the distal portion may be designed and mayinclude geometries to have a desired fit in corresponding distalportions of the medullary canal (such as, in some embodiments, thediaphysis). In accordance with these or other embodiments, the proximaland distal portions may be connected by a transition portion (which mayor may not include one or more faces defined by a constant radius ofcurvature) that facilitates an at least somewhat smooth transitionbetween the proximal and distal portion geometries.

Various aspects and embodiments of the present invention may alsoinclude methodologies for making the above-described orthopaedicimplants, or other orthopaedic implants. In accordance with someembodiments, such methodologies may include defining geometries for atleast parts of the proximal and distal portions of a first orthopaedicimplant by using data relevant to one or more bony anatomies appropriatefor the general size of the first orthopaedic implant size. Inaccordance with these or other embodiments, such methodologies mayfurther include defining geometries for at least parts of the proximaland distal portions of a second orthopaedic implant by using datarelevant to one or more bony anatomies appropriate for the general sizeof the second orthopaedic implant.

Orthopaedic implants, including implant sets, created using the abovemethodologies, or other methodologies, in accordance with certainaspects and embodiments of the present invention, may include at leastsome implants that do not “grow” uniformly with respect to other implantsizes. For example, in accordance with certain aspects and embodimentsof the present invention, orthopaedic implant sets may include someimplant sizes in which proximal portions of the implant's elongatedinsertion region increases to a greater degree than distal portions ofthe elongated insertion region with respect to a smaller implant size.

These, and other aspects and embodiments of the present invention aredescribed in more detail in the remainder of this document.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an anterior view of an orthopaedic implant in accordance withone embodiment of the present invention.

FIG. 2 is another anterior view of the orthopaedic implant of FIG. 1,illustrating various geometries of the implant.

FIG. 3 is another anterior view of the orthopaedic implant of FIG. 1,illustrating additional geometries of the implant.

FIG. 4 is a lateral view of the orthopaedic implant of FIG. 1.

FIG. 5 is a cross-section view of the orthopaedic implant of FIG. 1.

FIG. 6 is also a cross-section view of the orthopaedic implant of FIG.1.

FIG. 7 is also a cross-section view of the orthopaedic implant of FIG.1.

FIG. 8 shows a template in accordance with one embodiment of the presentinvention.

FIG. 9 is an anterior view of the outline of an orthopaedic implant inaccordance with one embodiment of the present invention.

FIG. 10 is a cross-section view of the orthopaedic implant of FIG. 9.

FIG. 11 is also a cross-section view of the orthopaedic implant of FIG.9.

FIG. 12 is a chart plotting proximal/distal growth ratios againstimplant size increases for a plurality of implants in accordance withone embodiment of the present invention.

FIG. 13 is a chart providing additional information about the chart ofFIG. 12.

FIG. 14 is also a chart providing additional information about the chartof FIG. 12.

FIG. 15 is also a chart providing additional information about the chartof FIG. 12.

FIG. 16 shows an anterior view of the outlines of a plurality oforthopaedic implants superimposed over one another in accordance withone embodiment of the present invention.

DETAILED DESCRIPTION OF DRAWINGS

FIG. 1 shows an orthopaedic implant 10 in accordance with certainaspects and embodiments of the present invention. As shown in FIG. 1,orthopaedic implant 10 may include an elongated insertion region 12.Elongated insertion region 12 may facilitate installing orthopaedicimplant 10 in, or otherwise associating orthopaedic implant 10 with, thebony anatomy. For example, in some embodiments, elongated insertionregion 12 may be at least partially inserted into a prepared or naturalmedullary canal of the bony anatomy.

The orthopaedic implant 10 shown in FIG. 1 is a femoral hip stem forimplantation into the medullary canal of a femur. The present invention,however, is not limited to femoral hip stems. Other aspects andembodiments of the present invention may include other femoral implants(including implants for the proximal, mid, and/or distal regions of thefemur), tibial implants, humeral implants, other implants for themedullary canal, or other types of orthopaedic implants for installationin or association with the bony anatomy. Thus, although the accompanyingFigures and the below description illustrate a femoral hip stemembodiment, other types of implants are within the scope of the presentinvention.

FIGS. 1-3 schematically illustrate some of the implant's 10 geometries.In these or other embodiments, however, additional or alternativemeasurements and constructs may be used to define the geometries of theimplant.

In the embodiments of FIG. 1, orthopaedic implant 10 defines alongitudinal axis 14. As shown, longitudinal axis 14 generally extendsbetween an upper portion 16 and a distal tip 18 of the implant 10 andmay roughly correspond to a anatomic axis of the bony anatomy for whichthe implant 10 is intended. It is not necessary, however, thatlongitudinal axis 14 extend between upper portion 16 and distal tip 18,or that longitudinal axis correspond to the bony anatomy's mechanicalaxis. In accordance with this or other embodiments of the presentinvention, orthopaedic implant 10 may define other longitudinal axes,which may or may not extend between the upper portion 16 and distal tip18 and which may or may not extend along the mechanical axis of the bonyanatomy for which the implant 10 is intended.

In the embodiments of FIG. 2, the elongated insertion region 12 isdivided into a proximal portion 20, a distal portion 22, and atransition portion 24. The proximal portion 20 shown extends from anosteotomy point 26 to the proximal end of transition portion 24, thetransition portion 24 shown extends from the distal end of proximalportion 20 to the proximal end of distal portion 22, and the distalportion 22 shown extends from the distal end of transition portion 24 tothe implant's distal tip 18. In accordance with other aspects andembodiments of the present invention, however, the proximal, distal andtransition portions (20, 22 and 24) may overlap and/or are notnecessarily defined by distinct boundaries. In still other embodiments,elongated insertion region 12 does not include a transition portion 24,and the proximal portion 20 may extend up to or overlap the distalportion 22. In still other embodiments, the proximal and distal portions20 and 22 may be reversed from the orientations shown in FIG. 2.

As discussed above, in some embodiments, the osteotomy point 26indicates the proximal end of the proximal portion 20. The osteotomypoint 26 may roughly correspond to the point where a resection plane (inthis embodiment, a proximal femur resection plane) intersects theimplant's medial face 28 when implanted. In other embodiments, theproximal portion 20 may be defined with respect to other structures orfeatures of the prepared or unprepared bony anatomy and/or the implant10 itself, and the implant 10 does not necessarily include an osteotomypoint 26.

In the embodiments shown in FIG. 3, a constant radius of curvature 100extends from center 102 and defines the curve or arc of the medial face28 in the proximal portion 20, and a second constant radius of curvature104 extends from center 106 and defines the curve or arc of the medialface 28 in the transition portion 24. Radii of curvature 100 and 104 maybe different, or the same, lengths. In the embodiments shown in FIG. 3,centers 102 and 106 are spaced apart from one another, although, inother embodiments, they may be the same.

In accordance with some of the embodiments of the present invention, thearcs defining the medial face, including the proximal portion 20 medialface, transition portion 24 medial face, or any other portions and/orfaces need not be defined by a constant radius of curvature. Instead,they can, in these or other embodiments, track parabolic paths,hyperbolic paths, elliptical sections, and/or can be any desired curvedshape. Thus, the medial faces of the proximal portion 20 and thetransition portion 24 (and any other portion) may be curves or arcsdefined in any desired manner. For example, the medial faces of proximaland transition portions 20 and 24 may be defined by a parabolic equationor another geometric or non-geometric equation instead of comprisingpart of a circle. In still other embodiments, the medial faces ofproximal and transition portions 20 and 24 are not subject to empiricaldefinition by a mathematic equation.

In other embodiments, the proximal portion 20 and the transition portion24 of the medial face 28 may be both defined by a single radius ofcurvature extending from a single center. In still other embodiments,the proximal portion 20, the distal portion 22, and the transitionportion 24 of the medial face 28 may be all defined by a single radiusof curvature extending from a single origin. In still other embodiments,neither the proximal portion 20, nor the distal portion 22, nor thetransition portion 24 are defined by a constant radius of curvature.

In accordance with the embodiments illustrated in FIGS. 1-3, theproximal portion 20 may generally correspond to the metaphysis and thedistal portion 22 may generally correspond to the diaphysis when theimplant 10 is implanted into the femur's medullary canal. In otherembodiments, the proximal portion 20, distal portion 22, and/ortransition portion 24 may overlap portions of the metaphysis and/ordiaphysis of the medullary canal.

In accordance with some of the aspects and embodiments of the presentinvention, the proximal portion 20 may be about 5 to about 55millimeters long, the distal portion 22 may be about 5 to about 55millimeters long, and the transition portion 24 may be about 15 to about65 millimeters long, although in other aspects and embodiments of thepresent invention, some or all of these portions may have lengthsfalling outside these ranges. In accordance with some embodiments, thelengths of the proximal, distal, and/or transition portions may increaseas the size of the implant increases.

In the embodiments shown in FIGS. 1-7, the elongated insertion region 12generally tapers from the proximal portion 20 to the distal portion 22,in both the anterior-posterior widths as well as the medial-lateralwidths. In other embodiments, elongated insertion region does not taperin one or both of the anterior-posterior and medial-lateral widths.

The tapered elongated insertion region 12 shown in FIGS. 1-7 defines aplurality of widths, including, but not limited to, proximal portion 20widths between the medial face 28 and the lateral face 30 of the implant10 (such as, for example, the medial-lateral proximal portion width 32shown in FIG. 2), distal portion 22 widths between the medial andlateral faces 28 and 30 (such as, for example, the medial-lateral distalportion width 34 shown in FIG. 2), proximal portion 20 widths betweenthe anterior face 36 and the posterior face 38 of the implant, anddistal portion 22 widths between the anterior and posterior faces 36 and38. Widths 32 and 34 are provided by way of example only. In theembodiments of FIGS. 1-7, because the elongated insertion region 12includes curved and tapered surfaces, it defines almost an infinitenumber of widths in both the anterior-posterior and medial-lateralaspects.

Both the proximal widths and the distal widths may be defined in othermanners in accordance with other embodiments and aspects of the presentinvention. For example, proximal, distal and/or transition portionwidths could also be defined as the distance between a medial, lateral,anterior, posterior and/or other face of the elongated insertion region12 and a longitudinal axis of the implant 10 (whether such axis is thelongitudinal axis 14 shown in FIG. 1 or another axis).

The embodiments shown in FIGS. 5-7 illustrate portions of elongatedinsertion region 12 that define a generally rectangular cross sectionwith rounded over corners. The present invention, however, is notlimited to orthopaedic implants 10 with rectangular cross sections. Inaccordance with other aspects and embodiments, elongated insertionregions 10 may define other geometries, including, but not limited to,cylindrical regions, conical regions, fluted regions, slotted regions,and/or other shapes.

In the embodiments shown in FIGS. 1-4, portions of faces 28, 30, 36 and38 (such as portions of the faces located in distal portion 22 ofelongated insertion region 12) and/or longitudinal axis 14 define anumber of angles. For instance, in the embodiments shown best in FIG. 2,the medial and lateral faces 28 and 30 of the distal portion 22 definean angle 44. As also shown in FIG. 2, the medial face 28 of the distalportion 22 and the longitudinal axis may define an angle 46. Similarly,the lateral face 30 of the distal portion 22 may define an angle 48. Inthese or other embodiments, other faces or surfaces of the elongatedinsertion region 12 may define other angles (including, but not limitedto, anterior and posterior faces 36 and 38 shown in FIG. 4).

In accordance with certain aspects and embodiments of the presentinvention, the angle 44 between the medial and lateral faces 28 and 30of the distal portion 22 is approximately six degrees. In these or otherembodiments of the present invention the angle 44 is betweenapproximately one and fifteen degrees. In still other embodiments, theangle 44 falls outside the aforementioned range. In some embodiments,angle 44, or other angles, may be varied in accordance with certainimplant 10 designs.

As discussed above, in accordance with certain aspects and embodimentsof the present invention, some or all of the portions of the elongatedinsertion region 12 may be shaped and/or sized to provide a desirablefit between the implant 10 and the medullary canal. Various aspects andembodiments of the present invention include methodologies for refiningand/or developing implant geometries to provide such a desirable fit.

FIG. 8 illustrates one methodology for defining at least some of thegeometries of the elongated insertion region 12 with some of the aspectsand embodiments of the present invention. FIG. 8 shows a template 200that may be used in conjunction with a templating study to developand/or refine implant geometries in accordance with certain aspects andembodiments of the present invention. Template 200 may be transparentsuch that it may be positioned over an x-ray, fluoroscopic or other typeof image of the bony anatomy and/or its associated medullary canal. Thetemplate 200 shown in FIG. 8 includes an outline of an initial implantgeometry 202, from both an anterior view as well as a medial view(although both views are not necessary). In accordance with otherembodiments of the present invention, template 200 may includeadditional or alternative views (including, but not limited to,posterior views, lateral views, and views from other angles or in otherplanes).

The anterior view shown in FIG. 8 includes a number of reference points(including references A through H) and other constructs for indicatingcertain geometries and aspects of the initial implant outline. In otherembodiments, template 200 may include additional or alternativereferences and/or constructs to indicate other geometries. As shown inFIG. 8, the template 200 may also indicate what image magnification andthe relevant implant size the template 200 is intended for, althoughsuch indications are not necessary in all embodiments. The same, oradditional, templates may be modified for use with other implant sizes.

Using one or more templates (such as the template 200 shown in FIG. 8),suitable geometries for one or more orthopaedic implants 10 may bedefined (including, but not limited to, a set of implants including aplurality of sizes). For example, in some embodiments, one may use thetemplate to evaluate whether the initial implant outline defines implantgeometries suitable for the structures of the bony anatomy (such as themetaphysis and diaphysis of the medullary canal) shown in the images.

If the initial implant outline geometries are not suitable, it may beindicated (on the template itself, on another form, or in some otherformat or medium) how the initial implant outline could be modified todefine a better-fitting implant. For example, if the proximal width atreference B did not indicate that such an implant would fit properly inthe bony anatomy, it could be noted that reference B needs to movemedially or laterally by a certain amount. By recording suchdiscrepancies with respect to these, or other reference points orconstructs, it can be recorded how the initial implant outline could bemodified to define a better-fitting implant.

In accordance with certain aspects and embodiments of the presentinvention, the templating study process can be repeated several timeswith other bony anatomies of the same general size. The accumulated datamay be subsequently averaged or otherwise processed to calculate orotherwise determine what changes should be made to the initial implantoutline to define a better-fitting implant. In some embodiments, thedata could be used to create a second initial implant outline, for asecond templating study to further refine the geometries of the implant.

In accordance with some embodiments, such a templating study could berepeated numerous times for various implant and bony anatomy sizes todevelop a set or series of implants.

Implant sets, in accordance with some aspects and embodiments of thepresent invention, do not include implants chosen from unrelated groupsof implants, but rather, may include a group of implants sharing commoncharacteristics or traits, but offered in a number of different sizes.Such common characteristics or traits may include, but are not limitedto, material properties, mechanical properties, indications for use,trade name or product grouping, geometric properties (such as, but notlimited to, stem shapes, neck shapes, neck offsets, etc. . . . ),features (such as, but not limited to, fluting, distal slots, presenceor absence of bone in growth material, or other features), or othercommon characteristics or traits or combinations of characteristics ortraits.

In accordance with aspects and embodiments of the present invention,methodologies other than a templating study may be used to definesuitable implant 10 geometries. For example, in some embodiments,previously collected data on bony anatomy geometries (such as internalwidths of various portions of the medullary canal) may be used tocalculate or otherwise determine suitable geometries for portions ofelongated insertion region 12. In still other embodiments, digitizedimages of bony anatomy can be processed, with or without the help ofcomputer functionality, to identify suitable geometries for portions ofelongated insertion region. Other methodologies may also be employed toidentify suitable geometries.

In accordance with some aspects and embodiments of the presentinvention, data points collected in accordance with one or more of themethodologies discussed above can be used to create one or moreorthopaedic implants 10 having elongated insertion regions 12 withdesirable bone loading and fixation properties, a more anatomicallycorrect geometry, and/or other desirable features. For example, inaccordance with some embodiments, the collected data can be used todefine geometries for proximal and distal portions 20 and 22 of theelongated insertion region 12 (such as medial/lateral widths 32 and 34)such that implantation of an appropriate sized implant 10 into themedullary canal of the bony anatomy results in desirable proximalloading of the bone while maintaining a close fit between the distalportion 22 of the elongated insertion region 12 and the correspondingdistal portion of the medullary canal.

In accordance with certain aspects and embodiments of the presentinvention, using one or more of the methodologies discussed above, acombination of those methodologies, or other methodologies, one maydefine one or more geometries for use in conjunction with an orthopaedicimplant 10 or a set or series of such implants 10. In some embodiments,many, if not all, of the geometries of the implant or implants may bedefined using such methodologies. In other embodiments, however, inaddition to the geometries defined using these methodologies, it may benecessary to develop additional geometries or use traditional geometriesto provide the implant manufacturer with sufficient data to construct animplant or an implant set.

For example, in accordance with aspects and embodiments of the presentinvention, although one or more of the methodologies discussed above mayidentify geometries for medial/lateral widths 32 and 34 in the proximaland distal portions 20 and 22, it may be too time consuming, orotherwise undesirable, to use such methodologies to define everygeometry necessary to construct an implant 10. It may be necessary toalso define, for example, anterior/posterior widths in the proximal anddistal portions, medial/lateral and/or anterior/posterior widths in thetransition portion, angles between the medial face, lateral face and/orlongitudinal axes, or other geometries. In such instances, traditionalimplant 10 geometries may be used, or other techniques may be employed,to supply various geometries not determined through one of the abovedescribed methodologies. For example, in one such embodiment, a constantradius 104 extending from center 106 may define the medial face of thetransition portion 24. The length and/or center 106 of the radius 104may be chosen such that it will define a connecting arc between thedistal end of the proximal portion 20 and the proximal end of the distalportion 22. In other embodiments, such a methodology is unnecessary andtransition portion 24 is either absent (e.g., the distal end of proximalportion 20 abuts the proximal end of distal portion 22) or the medialface of the transition portion 24 is defined in other ways, such as by aparabolic equation or in another manner.

In still other embodiments, the medial face in both the proximal andtransition portions 20 and 24 are defined by a single constant radiusextending from a center, such that the proximal portion includes themedial/lateral width or widths, defined using a templating study orother methodology but also transitions smoothly into the medial face ofthe distal portion. In other embodiments, one or more of the anglesdefined by the distal portion medial face, distal portion lateral faceand/or longitudinal axis 14 (or other axes), may be defined and/oradjusted such that the transition(s) between the various portions of theelongated insertion region 12 is/are smooth.

FIGS. 9-16 illustrate a set or series of orthopaedic implants 10 createdusing some of the methodologies and procedures discussed above inaccordance with aspects and embodiments of the present invention. In theembodiments shown in FIGS. 9-16, orthopaedic implants 10 are femoral hipstems and a templating study (using one or more templates similar to thetemplate 200 shown in FIG. 8) was conducted to identify medial/lateralwidths 32 (twenty millimeters distal to the osteotomy point 26) locatedin the proximal portion 20, and also medial/lateral widths 34 (eightymillimeters distal to the osteotomy point 26) located in the distalportion 22, for fifteen sizes of femoral hip stems (arbitrarily numbered1 through 15).

As shown by the dashed line in FIGS. 12-15, some typical femoral hipstem sets grow uniformly in the proximal and distal regions from size tosize (i.e. proximal growth divided by distal growth equals one). Unlikethe typical femoral hip stem set illustrated in the Figures, however,the implants 10 made in accordance with embodiments of the presentinvention do not always grow uniformly in the proximal and distalregions from size to size (proximal growth divided by distal growth doesnot always equal one, although for some size increases it does). InFIGS. 12-15, the “x” column indicates the medial/lateral width 32 inproximal portion 20, the “y” column indicates the medial/lateral width34 in distal portion 22, and the “z” column indicates length of theelongated insertion region 12.

As shown in FIGS. 12-15, growth rates do not have to have to beprecisely the same to have a growth ratio of approximately 1. As oneexample, with reference to the embodiment of FIG. 13, the size 2 implant10 includes a proximal portion width 32 of 19 mm (at a level about 20millimeters distal from the osteotomy point 26 level) (which may, insome embodiments, be represented as PW1 _(20mm)) and a distal portionwidth 34 of 7.4 mm (at a level about 80 millimeters distal from theosteotomy point 26 level) (which may, in some embodiments, berepresented as DW1 _(80mm)); whereas the size 3 implant 10 includes aproximal portion width 32 of 20.4 millimeters (at a level about 20millimeters distal from the osteotomy point 26 level) (which may, insome embodiments, be represented as PW2 _(20mm)) and a distal portionwidth 34 of 8.9 millimeters (which may, in some embodiments, berepresented as DW2 _(80mm)). In this example, the difference between theproximal portion widths 32 of the size 2 and 3 implants 10 is 1.4millimeters (which may be represented as PW2 _(20mm)−PW1_(20mm)=ΔPW_(20mm)) and the difference between the distal portion widths34 of the size 2 and 3 implants 10 is 1.5 millimeters (which may berepresented as DW2 _(80mm)−DW1 _(80mm)=ΔDW_(80mm)). In this example, thegrowth rates with respect to the proximal and distal portions isrelatively uniform. In other words, in accordance with this embodiment,ΔPW_(20mm (here,) 1.4 millimeters) is substantially equal to ΔDW_(80mm)(here, 1.5 millimeters) and thus the proximal to distal growth ratioshown in FIG. 13 between implant 10 sizes 2 and 3 may be plotted atsubstantially 1 (ΔPW_(20mm) divided by ΔDW_(80mm)) (in this case, about0.93).

In accordance with the embodiment shown in FIG. 13, however, theproximal to distal growth ratio is not always substantially equal to 1,since the proximal and distal portions of the implant 10 do not alwaysgrow in a uniform manner form one size to the next. For example, thesize 4 implant 10 includes a proximal portion width 32 of 21.7millimeters (PW1 _(20mm)=21.7) and a distal portion width 34 of 9.3millimeters (DW1 _(80mm)=9.3) and thus, with respect to comparing theproximal and distal growth rates of implant 10 sizes 3 and 4, ΔPW_(20mm)equals 1.3 millimeters and ΔDW_(80mm) equals 0.4 millimeters. In thisexample, the growth rates with respect to the proximal and distalportions is 3.25 and is thus not relatively uniform, (ΔPW_(20mm) is notsubstantially equal to ΔDW_(80mm) and ΔPW_(20mm) divided by ΔDW_(80mm)is not about 1). The above is offered as an example only, and does notdefine with mathematical precision the boundaries of “substantiallyequal.”

FIG. 16 shows the outlines of the orthopaedic implants 10 of FIGS. 9-15,shown superimposed over one another. As shown in FIG. 16, the medialfaces of the various implants 10 align with one another and the “growth”of the implants 10 occurs along the lateral faces of the implants 10.Thus, although not shown in FIG. 16, a single constant radius ofcurvature extending from a single center may define the medial faces ofthe proximal portions of the implants 10 and, similarly, a singleconstant radius of curvature extending from a single center may definethe medial faces of the transition portions of the implants 10. Also, asthe implants 10 shown in FIG. 16 grow, the shoulders 56 remainsubstantially aligned throughout the implant's growth, which mayfacilitate consistency in the location of where proximal fixation occursthroughout the range of implant sizes.

Changes, modifications, additions, and/or deletions may be made to thesystems, methodologies and devices described herein without departingfrom the spirit of the present inventions or the scope of the belowclaims.

1.-32. (canceled)
 33. A set of femoral hip stems, the set including atleast two different sizes of femoral hip stems, each femoral hip stemsize including a single piece elongated insertion region for insertioninto an intramedullary canal of a femur, the set of femoral hip stemscomprising: (a) a first femoral hip stem size having a first elongatedinsertion region extending along a first longitudinal axis, the firstelongated insertion region having a first medial face, a first lateralface, a first shoulder on the first lateral face, a first proximal widthextending between the first medial and lateral faces perpendicular tothe first longitudinal axis at a level of the first shoulder, and afirst distal width extending between the first medial and lateral facesperpendicular to the first longitudinal axis at a level 80 millimetersdistal to the first proximal width; and (b) a second femoral hip stemsize having a second elongated insertion region extending along a secondlongitudinal axis, the second elongated insertion region having a secondmedial face, a second lateral face, a second shoulder on the secondlateral face, a second proximal width extending between the secondmedial and lateral faces perpendicular to the second longitudinal axisat a level of the second shoulder, and a second distal width extendingbetween the second medial and lateral faces perpendicular to the secondlongitudinal axis at a level 80 millimeters distal to the secondproximal width; wherein the difference between the first and secondproximal widths is not substantially equal to the difference between thefirst and second distal widths.
 34. The set of femoral hip stems ofclaim 33, wherein the set further comprises a third femoral hip stemsize: wherein the third femoral hip stem size has a third elongatedinsertion region extending along a third longitudinal axis, the thirdelongated insertion region having a third medial face, a third lateralface, a third shoulder on the third lateral face, a third proximal widthextending between the third medial and lateral faces perpendicular tothe third longitudinal axis at a level of the third shoulder, and athird distal width extending between the third medial and lateral facesperpendicular to the third longitudinal axis at a level 80 millimetersdistal to the third proximal width; and wherein the difference betweenthe second and third proximal widths is substantially equal to thedifference between the second and third distal widths.
 35. The set offemoral hip stems of claim 34, wherein the third elongated insertionregion is longer than the second elongated insertion region, and whereinthe second elongated insertion region is longer than the first elongatedinsertion region.
 36. The set of femoral hip stems of claim 35, whereinthe first medial face defines a first metaphysis medial face portionhaving a first constant radius of curvature.
 37. The set of femoral hipstems of claim 36, wherein the first medial face defines a firsttransitional medial face portion distal to the first metaphysis medialface portion and having a second constant radius of curvature.
 38. Theset of femoral hip stems of claim 37, wherein the first constant radiusof curvature and the second constant radius of curvature each define alength that is substantially the same.
 39. The set of femoral hip stemsof claim 37, wherein the first constant radius of curvature and thesecond constant radius of curvature define lengths that are notsubstantially the same.
 40. A set of femoral hip stems, the setincluding at least three different sizes of similarly shaped femoral hipstems, each femoral hip stem including a single piece elongatedinsertion region for insertion into an intramedullary canal of a femur,the set of femoral hip stems comprising: (a) a first size femoral hipstem comprising a first metaphysis insertion region and a firstdiaphysis insertion region; (b) a second size femoral hip stemcomprising a second metaphysis insertion region and a second diaphysisinsertion region, wherein the second metaphysis and diaphysis insertionregions are wider than the first metaphysis and diaphysis insertionregions and define a change in width that is uniform along the first andsecond metaphysis and diaphysis insertion regions; (c) a third sizefemoral hip stem comprising a third metaphysis insertion region and athird diaphysis insertion region, wherein the third metaphysis anddiaphysis insertion regions are wider than the second metaphysis anddiaphysis insertion regions and define a change in width that is notuniform along the second and third metaphysis and diaphysis insertionregions.
 41. The set of femoral hip stems of claim 40, wherein the thirdsize femoral hip stem is longer than the second size femoral hip stemand the second size femoral hip stem is longer than the first sizefemoral hip stem.
 42. The set of femoral hip stems of claim 41, whereinthe first, second and third size femoral hip stems each comprise acurved medial face and a longitudinal axis; and wherein the curvedmedial faces are congruent in shape when the first, second and thirdsize femoral hip stems are aligned such that the longitudinal axes areparallel.
 43. The set of femoral hip stems of claim 42, wherein ametaphysis portion of the curved medial face of the first size femoralhip stem is defined by a first constant radius of curvature.
 44. The setof femoral hip stems of claim 43, wherein a transition portion of thecurved medial face of the first size femoral hip stem is defined by asecond constant radius of curvature; and wherein the transition portionof the curved medial face is distal to the metaphysis portion of thecurved medial face.
 45. The set of femoral hip stems of claim 44,wherein the first constant radius of curvature and the second constantradius of curvature each define a length that is substantially the same.46. The set of femoral hip stems of claim 44, wherein the first constantradius of curvature and the second constant radius of curvature definelengths that are not substantially the same.
 47. The set of femoral hipstems of claim 40, further comprising a fourth size femoral hip stemcomprising a fourth metaphysis insertion region and a fourth diaphysisinsertion region, wherein the fourth metaphysis and diaphysis insertionregions are wider than the third metaphysis and diaphysis insertionregions and define a change in width that is uniform along the third andfourth metaphysis and diaphysis insertion regions.
 48. The set offemoral hip stems of claim 47, wherein the fourth size femoral hip stemis longer than the third size femoral hip stem.
 49. A pre-made set offemoral implants, comprising a plurality of femoral implants: (a)wherein each femoral implant in the set includes an insertion portion,the insertion portion including a medial face, a lateral face, alongitudinal axis, and a length; (b) wherein at least some of theplurality of femoral implants have different insertion portion lengths;(c) wherein the plurality of femoral implants are configured such thatcurved portions of their insertion portion medial faces are congruent inshape for at least eighty millimeters along their longitudinal axes whenthe plurality of femoral implants are aligned such that the longitudinalaxes of the insertion portions are parallel.
 50. The pre-made set offemoral implants of claim 49, wherein a distal portion of the insertionportion medial face and a distal portion of the insertion portionlateral face of each of the plurality of femoral implants define aninsertion portion medial-lateral taper angle.
 51. The pre-made set offemoral implants of claim 50, wherein each of the plurality of femoralimplants has the same insertion portion medial—lateral taper angle. 52.The pre-made set of femoral implants of claim 51, wherein each femoralimplant in the set includes an insertion portion distal anterior faceand an insertion portion distal posterior face, and wherein theinsertion portion distal anterior face and the insertion portion distalposterior face define an insertion portion anterior-posterior taperangle.
 53. The pre-made set of femoral implants of claim 51, wherein aproximal portion of the insertion portion medial face of each of theplurality of femoral implants defines a constant radius of curvature,and each of the plurality of femoral implants has the same constantradius of curvature.
 54. A pre-made set of femoral implants, comprisinga plurality of femoral implants: (a) wherein each femoral implant in theset includes an insertion portion, the insertion portion including amedial face, a lateral face, a longitudinal axis, and a length; (b)wherein at least some of the plurality of femoral implants havedifferent insertion portion lengths; (c) wherein the plurality offemoral implants are configured such that curved portions of theirinsertion portion medial faces are congruent in shape for at leasttwenty millimeters along their longitudinal axes when the plurality offemoral implants are aligned such that the longitudinal axes of theinsertion portions are parallel; (d) wherein a distal portion of theinsertion portion medial face and a distal portion of the insertionportion lateral face of each of the plurality of femoral implants definean insertion portion medial-lateral taper angle; and (e) wherein atleast some of the plurality of femoral implants have substantially thesame insertion portion medial-lateral taper angle.
 55. The pre-made setof femoral implants of claim 54, wherein all of the plurality of femoralimplants have substantially the same insertion portion medial-lateraltaper angle.
 56. The pre-made set of femoral implants of claim 55,wherein each femoral implant in the plurality of femoral implantsincludes an insertion portion distal anterior face and an insertionportion distal posterior face, and wherein the insertion portion distalanterior face and the insertion portion distal posterior face define aninsertion portion anterior-posterior taper angle.
 57. The pre-made setof femoral implants of claim 55, wherein a proximal portion of theinsertion portion medial face of each of the plurality of femoralimplants defines a constant radius of curvature, and each of theplurality of femoral implants has the same constant radius of curvature.